I ran into the same problem I ran into a few months ago. Anytime I try to send a text/multimedia message it will just read "Please Wait.." then finally "Try Again Later". Turns out that I didnt fix it last time, just a fluke that it fixed itself.
This problem fixes itself, sometimes after a few minutes sometimes a few days. I try fooling around with my settings but there isnt anything to change and it will end up fixing itself.
Has anyone ran into this problem? Any help would be appreciated. Thanks!